Yep, there should be a notch at one end of the SID chip and the corresponding socket. In addition, Pin 1 on the chip might be marked with a spot. The notch on the socket is closer to Pin 1 than Pin 28.

As an owner of a Catweasel mk4 with 2 sid chips installed that has been unable to get them working since the new cw_config application was added to the drivers can I ask what windows programs support the Catweasel and has anyone managed to make them work the current beta drivers?

The SID chip socket allows Catweasel users to play SID chiptunes on the real chip instead of relying on software emulation for original sounding SID playback. The WinVICE emulator supports the Catweasel's SID features starting with version 1.13.

I have Catweasel MK4 with a 6581 SID chip installed. Windows 7 32b has detected it and the driver is correctly installed (shown OK on devices list)...but, Acid64 doesn't detect it so I am unable to play C64 samples. Did I miss any step on installation, please??